moq C. Jennings
Internet-Draft Cisco
Intended status: Standards Track 21 October 2024
Expires: 24 April 2025
Serialization of MoQ Objects to Files
draft-jennings-moq-file-00
Abstract
This specification provides a way to save the meta data about each
MoQ Object in one or more files as well as pointers to other files
that contain the contents of the object. Separating of the meta data
and payload data allow the payload data to remain in files that are
used for other purposes such as serving HLS/DASH video. This format
makes it easier to test and develop caching relays and create test
data they can serve to client.
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This Internet-Draft will expire on 24 April 2025.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Internet-Draft Moq Object Files October 2024
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. JSON Meta Object . . . . . . . . . . . . . . . . . . . . . . 2
3. File Naming . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. MOQT Track DataFile . . . . . . . . . . . . . . . . . . . . . 3
5. Playback . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Time Object Example . . . . . . . . . . . . . . . . . . . 4
7. IANA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
8. Security Considerations . . . . . . . . . . . . . . . . . . . 4
9. Normative References . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
This specification defines a way of serializing the MoQ Objects
defined in [MOQT] into files. The payload data and the meta data are
separated into separate files to allow reuse of existing files with
the payload data.
2. JSON Meta Object
The .moq files consist of an array of one or more JSON objects. Each
JSON object contains information about the MOQT object as well as
pointers to the where the original data can be found.
The follow fields are defined for JSON object:
* namesSpace: Array of strings that have a Base64 encoded version of
the data in each tuple of MOQT Track Namespace.
* trackName: string with Base64 encoded version of the MOQT
TrackName.
* objectID: integer corresponding to the MOQT ObjectID
* groupID: integer corresponding to the MOQT GroupID
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* subGroup: integer corresponding to the MOQT SubGroup
* publisherPriority: integer corresponding to the MOQT Object
publisherPriority
* maxCacheDuration: integer corresponding to the MOQT
maxCacheDuration
* publisherDeliveryTimeout: integer corresponding to the MOQT
publisherDeliveryTimeout
* receiveTime: time was created or time original was received
received by the relay. This is in milliseconds since the unix
epoch.
* dataFile: string with relative path name to the file that stores
the MOQT Object, including header and its payload data.
* dataOffset: number of bytes into file where objects starts ( 0 is
first byte of file )
* dataLength: number of bytes of data in the object
Any extension attributes should also be saved using a field name
formed by the string "ext" then the base 10 integer representation of
the extension type ID.
3. File Naming
It is RECOMMENDED to use a URL encoding version of the FullTrackName
with a suffix of ".moq" as the file name for the meta file. In this
context FullTrackName is concatenation of Track Namespace with the
TrackName, separated by "/". Optionally, the filename can be
extended with information about group as needed.
4. MOQT Track DataFile
When saving a whole MOQT Track to a file, a common way to do this
would be to make one ".dat" file with all the object data and another
".moq" file with all the array of JSON object for each MOQT Object.
An implementation can choose to have one file per MOQT group. In
such a case, it does so by creating one metadata (".moq") file and
one datafile (".dat") containing data for each object in the MOQT
group.
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5. Playback
Some use cases will want to just load a file into the relay as
quickly as possible. Other may decide to remade the track name to a
new track name publish the objects at a rate based on differences of
the receiveTime of the JSON objects.
6. Example
TODO More complete example
6.1. Time Object Example
Data file named time1.dat contains:
{"time":17294570764566}
Metadata file contains:
[
{
"namesSpace": "bW9xOi8vbW9xLXRpbWUuYXJwYS90aW1lLXYxLw=",
"trackName": "bWFjOjcyOjVjOmYwOjdjOmJmOmIw",
"objectID": 0,
"groupID": 123,
"subGroup": 0,
"publisherPriority": 0,
"maxCacheDuration": 3600000,
"publisherDeliveryTimeout": 60000,
"receiveTime": 1729457464000,
"dataFile": "time1.dat",
"dataOffset": 0,
"dataLength": 25
}
]
7. IANA
TODO file extension registrations.
8. Security Considerations
TODO
9. Normative References
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[MOQT] Curley, L., Pugin, K., Nandakumar, S., Vasiliev, V., and
I. Swett, "Media over QUIC Transport", Work in Progress,
Internet-Draft, draft-ietf-moq-transport-06, 19 September
2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
moq-transport-06>.
Author's Address
Cullen Jennings
Cisco
Email: fluffy@iii.ca
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